Premiere failing to save path

I have a preset that contains 2 lumetri effects with mask paths.

I edit this path into a new shape, animate it, and then copy the mask to the other lumetri effect.
Save the project and when I open it the mask is missing. 
This has now happened twice and today it represents about 2-3 hours of wasted work.  All of my backups and auto-saves exhibit the same feature: no mask. 

Windows 11 22h2 
PPRO 23.6.2
Note - I just tested this and was able to reproduce the bug once, but not twice yay
I applied a blank lumetri effect (preset) to a 5k DJI mp4 sequence that contained a nested sequence which contained the  clip playing at -100% (ie reversed).  I added the mask, animated it. I saved the project, closed premiere, re-opened premiere and loaded the project. The first 2 keyframes were remembered, but the final one was not saved.   

ps

I use it to  create a stroke on a layer because of premiere's on-going CUDA time-remapping bug (a bug that is so old it now outdates at least one version of this forum, and 2 adobe bug reporting platforms https://www.youtube.com/watch?v=CoUYqRoHXEo)